Two-dimensional capacitive sensor fields are in many cases used as control panels (touch pads) for vehicle functions, for example to operate a radio or a navigation system. The capacitive sensor field is preferably arranged in the instrument panel of a motor vehicle and is combined with a display or a mask displaying the corresponding vehicle functions. According to the prior art, such touch pads are produced using relatively thick circuit boards to minimize crosstalk between the leads of the electrodes and the electrodes themselves and to permit an accurate capacity measuring at the respective electrode. The capacity to be measured is generated by the interaction between the respective electrode of the capacitive sensor field and an object lying in an isolated manner on a contact plate and assumed to be grounded, for example a pin specifically provided therefor or the finger of a user. To convert the capacities measured at the electrodes of a capacitive sensor field into appropriate position and/or proximity signals which can be transmitted to the vehicle electronics for further evaluation, a capacitive sensor usually comprises in addition to the sensor field an evaluation unit or evaluation electronics which can of course also be integrated into other electronic components of the vehicle.
The thick circuit boards used to manufacture known sensor fields represent on the one hand a cost factor. On the other hand, a thick and accordingly mechanically rigid circuit board leads to restrictions with respect to the application possibilities of the capacitive sensor field. For example, the adaptation of the sensor field to a desired spatial shape of the touch pad is possible to a limited extent only, without the rigid circuit board having to be adapted already during manufacture to this spatial shape, e.g. to a determined convex or concave surface of the touch pad.